The Fate of Nucleic Acid Bases in Ladino Clover during Ensilage

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  • ラジノクローバーサイレージ熟成中における核酸塩基の消長について
  • ラジノクローバーサイレージ熟成中における核酸塩基の消長について〔英文〕
  • ラジノクローバー サイレージ ジュクセイチュウ ニ オケル カクサン エンキ

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Abstract

The presence of unaccounted nitrogen in silages has been reported by many workers and this study was undertaken to make clear a part of the unaccounted nitrogen by measuring nucleic acid bases. Ladino clover was ensiled with and without glucose, formic acid or formaldehyde in order to prepare different types of silages. Silages of moderate quality were obtained from the untreated herbage. Glucose treatment improved silage quality by enhancing lactic fermentation. Formic acid was effective in restricting silage fermentation but formaldehyde treatment rather enhanced clostridial fermentation. More than 7% of the total nitrogen of the herbage was present as nucleic acids and parts of which were decomposed during ensilage. The decomposition rate was lowest (68%) in the formic acid treated silages and the highest (85%) in the untreated silages with statistical significances among the three silages including the glucose treated ones. The ratios of DNA to RNA in the remaining nucleic acids in every silage prepared were similar (r=0.87, P<0.01). Except for the formaldehyde treated silages, the increase of free guanine during ensilage was correlated (r=0.95, P<0.01) with the decrease of nucleic acids. Free adenine was observed to be unstable compared with guanine. The recovery of the nitrogen of decomposed nucleic acids in free purines was 15% in average. Although quantitative determination of pyrimidines could not be made, it was confirmed that the free pyrimidine content of the silages was greater than the free purine content of them. The absorbances of cytosine and uracil extracted from the silages with some interfering substances had significant correlations with guanine content (r=0.90, P<0.01 and r=0.74, P<0.05, respectively) and decomposition rate of nucleic acids (r=0.93, P<0.01 and r=0.80, P<0.01, respectively) except for those of the formaldehyde treated silages. Nucleosides were not present in both the herbage and the silages. Nucleotides determination was not made. Besides peptide-, amino-, amide-, amine-, nitrate-, purine- and ammonia-nitrogens, there were still some unaccounted nitrogens in the non-protein nitrogen fractions of the herbage and silages. Parts of the unaccounted nitrogens were pyrimidine bases.

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